1 files changed, 3 insertions, 0 deletions
diff --git a/src/string.c b/src/string.c
index 719be3ff5..8a9ed8a24 100644
--- a/src/string.c
+++ b/src/string.c
@@ -216,6 +216,9 @@ mrb_value
 mrb_str_new(mrb_state *mrb, const char *p, size_t len)
 {
   struct RString *s;
+  if ((mrb_int)len < 0) {
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "negative string size (or size too big)");
+  }
 
   s = str_new(mrb, p, len);
   return mrb_obj_value(s);